On 6-10-2016 10:07, Gucea Doru wrote: > On Wed, Oct 5, 2016 at 11:12 AM, Arend Van Spriel > <arend.vanspriel@xxxxxxxxxxxx> wrote: >> On 4-10-2016 13:39, Gucea Doru wrote: >>> On Sat, Oct 1, 2016 at 2:52 PM, Arend van Spriel >>>> <arend.vanspriel@xxxxxxxxxxxx> wrote: >>>>> >>>>> >>>>> On 29-09-16 13:32, Gucea Doru wrote: >>>>>> On Tue, Sep 27, 2016 at 12:03 PM, Gucea Doru <gucea.doru@xxxxxxxxx> wrote: >>>>>>> What is the decision triggering the exit from the PS mode immediately >>>>>>> after the ping request? I am asking this because 802.11 PS legacy >>>>>>> specifies that the client should wait for a beacon with TIM set in >>>>>>> order to wake up: in my case, there is no beacon between the ping >>>>>>> request message and the Null frame that announces the exit from the PS >>>>>>> mode. >>>>>> >>>>>> >>>>>> Any help would be highly appreciated :) >>>>> >>>>> Actually though I already sent you are reply, but alas here it is. >>>>> >>>>> bcmdhd is our aosp driver. I am maintaining the upstream brcm80211 >>>>> drivers. Regardless your question is more for firmware running on the >>>>> device. So like the same behavior would be observed when using brcmfmac >>>>> with same firmware. >>>>> >>>>>> IEEE Std 802.11-2012, section 10.2.1.8 specifies that "when the STA >>>>>> detects that the bit corresponding to its AID is 1 i the TIM, the STA >>>>>> shall issue a PS Poll". In my capture there are cases when the STA >>>>>> exits the PS mode without waiting for a beacon. >>>>> >>>>> It is a bit tricky, but the standard does not explicitly say the STA >>>>> should be in power-save at any other time. So it is difficult to say >>>>> what event occurred on the STA side to exit PS mode. Also STA means >>>>> P2P-Client as you say. That means that you have multiple interfaces: >>>>> regular STA and P2P-Client. So is the STA connected to some other AP or >>>>> just not connected. wpa_supplicant will do intermittent scan or initiate >>>>> scheduled scan by which firmware will scan at a certain interval. That >>>>> is just some things I can come up with and I am sure there are more. >>> >>> I agree that there may be some events belonging to the regular STA >>> interface that could trigger the Null Frame (which includes the exit >>> from PS Mode). However, I would expect to see some management frames >>> in the air before/after the Null Packet (e.g.: a Probe request in case >>> of a scheduled scan). But in my case the trigger for the Null frame >>> seems to be the ping request packet, the scenario is the same every >>> time: ping request -> Block ACK -> Null Frame (Wireshark trace >>> confirms this behavior). >>> >>> I thought that you had a power save optimization algorithm that keeps >>> the card on a few milliseconds just to see if we can have a fast reply >>> from the peer. Does this ring a bell? :) >> >> It does not. That would be implemented in firmware. As said I am working >> on brcmfmac/brcmsmac. So bcmdhd and firmware are not my expertise. >> > > Arend, could you please redirect me to a Broadcom firmware maintainer? Can you please elaborate on your platform, broadcom chipset, and what version of bcmdhd you are using. Regards, Arend
